Pena served as the flex guy of the White Sox's pitching staff, starting three games and serving in a mix of long and short relief for the remainder of his 100.2 innings. He only had a 56:45 K:BB in 2010, but that rate is not reflective of his career thus far. He should occupy a flex role once again in 2011, with more work in the middle innings than the late ones.

2010

The White Sox acquired Pena from Arizona in July, and he made an impact as a middle reliever. He was fairly hittable, but struck out 29 and walked only nine in 36 innings. He should factor into the eighth-inning discussion along with J.J. Putz in 2010, and will likely be second in line to close out games should something happen to Bobby Jenks.

2009

The early-season emergence of Brandon Lyon as the D-Backs' closer put Pena's opportunity to work the ninth inning on hold, while Chad Qualls ended up taking over the role down the stretch when Lyon and trade deadline acquisition Jon Rauch were struggling. As for Pena, his strikeout rate (6.44 K/9IP) remained in line with his career mark, while he managed to cut back on his walks (2.11 BB/9IP) and home runs (0.62 HR/9IP). If he had been able to avoid a spike in BABIP (.329), Pena would have finished with an ERA closer to three than the 4.33 he ended with. All signs point to another season as a valuable set-up man for the D-Backs. Pena will also remain in the mix for the closer's role, and he could be given a chance to compete for the job during spring training, but manager Bob Melvin suggested that Qualls would have the opportunity to keep the job after pitching well in September.

2008

Pena enters spring training as the odds-on favorite to win the closer's job in the Arizona bullpen following the trade of Jose Valverde to Houston in December. At press time, GM Josh Byrnes wouldn't tip his hand regarding who will officially get the first crack at the job, but we like Pena and his mid-90s fastball and good slider to slot into the role with Juan Cruz, Brandon Lyon and newly acquired Chad Qualls to set the table for him in the seventh and eighth innings.

2007

Pena was a terror after being converted to the bullpen, perhaps to his detriment. The D'backs yanked him into the major league pen after just three months, something for which he wasn't ready. Of the Diamondbacks' dozen righthanded relievers, Pena probably has the highest upside.

2006

The pitching artist formerly known as Adriano Rosario (he changed his name in 2004) actually competed for a major league rotation spot last spring. Luckily for him, he developed mild elbow trouble and had to start the year at Double-A. He clearly wasn't ready for the bigs. He moved from the Texas League in 2004 to the Southern League in 2005, and his ERA and WHIP actually increased, which isn't a good sign. Pena could compete for a rotation spot again in 2006, but he likely needs at least another year in the minors.

2005

At press time, it was still unclear if Pena, who was formerly known as Adriano Rosario, would be allowed back into the States to play baseball in 2005 after an INS investigation in the Dominican Republic showed that Pena was more than three years older than he'd told the Diamondbacks when he was signed. Even if he's allowed to go to spring training, now that we know Pena is 23, his numbers don't look that great anymore.

2004

As we write this, Rosario is in the midst of a winter campaign (first in the Arizona Fall League, and then the Dominican Winter League) that has D-Backs' brass thinking that Rosario, who'll turn in 19 in May, could spend his next birthday in a major league uniform. He enjoyed a fine season at Single-A South Bend in 2003 (only three home runs allowed in addition to the numbers above), and if the coaches that worked with Webb, Villarreal, Capuano, Valverde and others over the past few years like him the best, maybe he's pretty good. Find a spot for him on your deep keeper league reserve list now and see what develops.